.content{
    width: 640px;
    height: 640px;
    margin: 50px auto;
    position: relative;
}
.btn{
    width: 100%;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    background-color: rgba(0,0,0,0);
    z-index: 1;
}
.btn button{
    background: none;
    border:none;
    background-size: 100% 100%;
    cursor: pointer;
    outline: none;
    position: absolute;
    left: 50%;
    top: 50%;
}
.startBtn button{
    width: 200px;
    height: 150px;
    background-image: url('../images/btn1.gif');
    margin-left: -100px;
    margin-top: -75px;
}
.pauseBtn{
    display: none;
}
.pauseBtn button{
    width: 70px;
    height: 70px;
    background-image: url('../images/btn4.png');
    margin-left: -35px;
    margin-top: -35px;
}
#snakeWrap{
    position: relative;
    width: 600px;
    height: 600px;
    background: #FCE4EC;
    border: 20px solid #F8BBD0;
}
.snakeHead{
    background-image: url('../images/snake.png');
    background-size: cover;
}
.snakeBody{
    background-color: #9CCC65;
    border-radius: 50%;
}
.food{
    background: url('../images/food2.png') no-repeat;
    background-size: 100% 100%;
}